Liquid crystalline polymers (LCPs) are well-known in the prior art, and because they can withstand high temperatures, they are useful for molding articles which are exposed to high temperatures, such as ovenware. For practical uses in ovenware, the materials are required to have excellent thermal resistance, electrical properties, good hardness and impact strength, and high tensile and flexural strength. For example, ovenware should not change in shape even at 200 to 400.degree. C.
U.S. Pat. Nos. 4,626.557 and 5,096,957 disclose molding compositions comprising mixtures of wholly aromatic polyesters and fillers of up to 65 wt. % talc having a particle size distribution in which over 95% of the particles being less than 40 microns. The compositions can be molded into ovenware having good mechanical properties and pleasing visual appearances. However, these compositions when used continuously in an injection molding operation and over a period of time, continually generate decomposition products that become deposited on the mold or in the vents. The problem, commonly termed "plate-out," may cause staining or discoloration in the molded ovenware as well as blockage in the mold. It then becomes necessary to stop the molding operation at regular intervals to clean the mold and associated processing equipment.
The art has thus continued to seek out solutions to the plate-out problems, and more particularly for compositions with minimum decomposition during molding while still possessing the excellent mechanical, electrical, and thermal properties required in ovenware applications.